The efficiency of stripper is the key factor for the decomposition of the unconverted ammonium carbamate from the urea reactor. The stripper is the heart of urea plants either ammonia stripping or CO2 stripping process. The sample of reactor outlet and stripper outlet liquid is done daily or when required but vapour is not possible to analyse so it is to be calculated by difference. How much vapour be calculated by difference. How much vapour decomposed? The stripping efficiency is calculated by CO2 stripping, how much CO2 stripped i.e., efficiency but in the CO2 stripping process the method is different because the CO2 process the method is different because the CO2 is fed in the stripper bottom for more decomposition by heat & mass transfer. In this paper, the calculation procedure will be described in detail for both stripping processes. In the CO2 stripping process N/C meter can also be provided in the reactor outlet line while vapour is separated via the opt of the reactor. But in ammonia stripping process all the two-phase mixture feed goes to the stripper without vapour separation first.